Anesthetic agents (ketamine, halothane and enflurane) were administered to rats who were made hypertensive by renal artery clipping. Significant differences in blood pressure were seen with anesthesia and when the renin-angiotensin system was inhibited by saralasin (a competitive inhibitor of angiotension II). Significant differences were also seen in rats who had been hemorrhaged to 40 torr for one hour once an inhibitor of the renin-angiotensin system had been infused. Current work using microspheres is attempting to define who inhibitors of the renin-angiotensin system alter cardiac output.